Bio-H₂ potential (BHP) of industrial food waste (FW) admixed with waste activated sludge (WAS) was evaluated at a range of C:N. The seed inoculum was prepared comparing earlier studies enhancing the BHP potential. Co-blending improved the potential value of individual feed stock of food waste by increasing the cumulative biogas production. The optimum BHP noticed at C:N of 15, with a blend containing about 31.4% sewage sludge. As the fraction of food waste in the blend increased, pH value decreased and reached to 4.2 with 100% FW alone, this cause significant decrease in ammonia and alkalinity levels. On the contrary VS removal efficiency increased by increasing the fraction of food waste. The highest ѱ potential observed in the present study was correlated with high percentage of bio-H₂ production. Under natural pH condition, C:N of 5.4 (WAS) alone produced relatively higher amount of bio-H₂ at a short elapsed time. Interestingly, the highest activity of biomass (as ATP) was also corroborated well with high BHP potential. However, biomass activity in BHP was found lower than BMP results; correspond well with previous reported studies. The increasing C:N was corroborated well with BHP potential. High degree of hydrolysis was observed at both low and high C:N ratio; presumably attributed to protease hydrolysis at low C:N and acid hydrolysis at high C:N respectively. Further, study concludes the optimum C:N and pH produce fermentative bio-H₂ using food waste and sewage sludge.